KAMLOOPS, B.C. -- British Columbia's transportation minister says a highway crash that injured dozens of tour bus passengers last month was most likely caused by driver error.

The bus flipped into a ditch on the Coquihalla Highway south of Merritt, B.C., ejecting multiple passengers and leaving all 56 people aboard with varying injuries.

RCMP have already ruled out speed as a cause of the accident, and provincial Transportation Minister Todd Stone says that mechanical failure has also been eliminated as a factor following an inspection of the bus.

A final police report still has to be filed, but Stone told Kamloops radio station CHNL that driver fatigue potentially led to the crash and his ministry will review the length of time that drivers can operate a vehicle before there is a mandated rest.

The bus was operated by Western Bus Lines, and someone who answered the phone at the company's Kelowna office said no one is available to speak to Stone's comments.

The bus crashed on Aug. 28 while returning to Vancouver from a tour of the Rocky Mountains with passengers from Canada, mainland China, Hong Kong, Taiwan and the United States.